1. Technical Field
The present disclosure relates to an electrostatic discharge protection device, in particular, to an electrostatic discharge protection device with embedded silicon controlled rectifier (SCR) and an electronic device thereof.
2. Description of Related Art
To protect electronic elements (e.g. integrated circuit) from encountering electrostatic discharge and being damaged during the design, production, and use processes. Thus, there is usually an electrostatic discharge protection circuit set on the path connected to the bonding wire in the electronic device to protect the inner circuit of the electronic device.
Please refer to FIG. 1, FIG. 1 is a circuit diagram of an electronic device with a traditional electrostatic discharge protection device. As shown in FIG. 1, the electronic device comprises an input/output end 2′, a supply voltage end VDD, a ground end GND, and an electrostatic protection device and chip 6′, wherein the electrostatic protection device consists of the diode 3′, 4′ and an plug-in clamp circuit 5′ (consisted of a plurality of transistors and a resistor for instance).
An anode of the diode 3′ and a cathode of the diode 4′ are connected to the input/output end 2′. A cathode of the diode 3′ is connected to the supply voltage end VDD and an anode of the diode 4′ is connected to the ground end GND. The clamping circuit 5′ is connected between the supply voltage end VDD and the ground end GND. The chip 6′ is connected to the supply voltage end VDD, the input/output end 2′ and the ground end GND. The chip 6′ is equivalent to the combination of multiple transistors; for instance, one of the transistors 7′ is connected to the input/output end 2′ and the ground end GND. The ground end GND is connected to a ground voltage, and the supply voltage end VDD is connected to a supply voltage, wherein the supply voltage is larger than the ground voltage.
When the input/output end 2′ encounters the electrostatic discharge (positive voltage), there will be electrostatic discharge conducting path, path1, and more details will be explained in the following. In the electrostatic discharge conducting path, path1, the electrostatic discharge current will pass through the forward diode 2′ to the voltage supply end VDD. Then, the electrostatic discharge current passes through the triggered clamping circuit 5′ to the ground end GND. At that moment, the voltage of the input/output end 2′ is Vth+Ipath1(RVDD+RCLAMP), wherein Vth is the forward conducting voltage of the diode 3′, Ipath1 is the electrostatic discharge current of the electrostatic discharge conducting path, path1. Furthermore, RVDD and RCLAMP are respectively the resistor of the wire connected to the voltage supply end and the resistor of the clamping circuit 5′. Thus, if the length of the wire connected to the voltage supply end is too long (i.e. RVDD is too large), the voltage of the input/output end 2′ may be large, so that the chip 6′ will be damaged; for instance, the transistor 7′ will breakdown and be damaged.